Canine Infectious Respiratory Disease: New Research Insights

Canine Infectious Respiratory Disease Complex (CIRD), often called “kennel cough,” is a highly contagious respiratory disease of dogs. It is caused by numerous bacteria and viruses such as Bordetella bronchiseptica, various Mycoplasma bacteria, parainfluenza virus, canine influenza virus, and more. The classic clinical sign of CIRD is a dry, honking cough, but other signs including eye or nose discharge and fever can been seen. Pneumonia can develop, but is often due to bacterial infections that take hold when the immune system is weakened by the primary infectious agent.

Thankfully, most cases of CIRD resolve within 7-10 days with supportive care consisting of rest and cough suppressants. However, in 2022 and 2023, there were increased reports of CIRD cases in the United States. Some cases were unusually severe and did not respond to standard treatments or resolve within the usual period of time. This led to intense debate regarding whether this was a true increase in disease incidence or just more media coverage. If there was an actual increase in cases, was it caused by a new infectious agent? Were dogs not as resistant to typical respiratory disease agents because they were isolated and/or not vaccinated during the COVID-19 pandemic? Or were there other factors at play?

A New Infectious Agent?
At the University of New Hampshire’s New Hampshire Veterinary Diagnostic Laboratory, veterinary pathologist Dr. David Needle asked surrounding veterinary clinics to submit swabs from the noses and throats of dogs showing signs of CIRD to study what was really happening. Collaborating with scientists at the University of New Hampshire’s Hubbard Center for Genome Studies, Dr. Needle and his team examined the genetic material collected from the respiratory tract of these sick dogs. They found genetic material that was not a match for any known dog respiratory pathogens. However, the DNA did resemble that of a known human respiratory pathogen.

David Needle, DVM, DACVP

“The pathogen is a small bacterium with a relatively small amount of genetic material,” Dr. Needle says. “It really looks like it’s something new to the canine respiratory microbiome – a new pathogen that has not been described before.”

Microbiome: the community of microorganisms that live in a particular environment.

More Research
Dr. Needle needed funding to pursue the follow-up studies required to understand this new disease-causing agent. Thankfully, he reached out to the AKC Canine Health Foundation (CHF), a nonprofit organization dedicated to advancing the health of all dogs by funding scientific research and sharing health information to help prevent, treat and cure canine disease. CHF seeks to support ground-breaking research in response to the ever-changing health needs of dogs. It was a perfect match!

With more than $300,000 invested by CHF and its donors, Dr. Needle and his team are now studying the exact genetic composition of the CIRD pathogen (CHF Grant 03273: Characterizing Potential Novel CIRD Pathogen and CIRD Microbiome Perturbations). They are also examining the entire microbiome of the canine respiratory tract, identifying which viruses, bacteria, and fungi are present in healthy dogs and those with various respiratory diseases.

“This information will greatly improve our understanding of canine respiratory disease,” Dr. Needle says. “We can look at how a dog’s respiratory tract responds to various infectious agents. Ultimately, we hope to use this information to develop treatment strategies that help all dogs recover from CIRD and in a shorter period of time.”

Dr. Needle remains enthusiastic about identifying and describing the new respiratory pathogen. “We are going to find this bacterium!” he continues. “The work is intellectually stimulating. But even better, it serves the public and our animal communities. I’m a dog owner too and happy that we can impact the clinical care of our pets.”

By investing in critical research like this study, CHF demonstrates its commitment to addressing the emerging health threats and complex issues that impact the well-being of all dogs. The Foundation also provides infectious disease fact sheets on CIRD and other diseases at www.akcchf.org/factsheets to help dog owners be informed and active partners in protecting their dog’s health. Stay tuned for CIRD research results and learn more about CHF’s work at www.akcchf.org.